1. Field of the Invention
The present invention relates to a mechanism for moving a target object and a charged particle beam writing apparatus, and particularly to an electron beam writing apparatus which irradiates an electron beam on a target object while variable-shaping the electron beam, and a stage for use in the electron beam writing apparatus to place the target object thereon.
2. Related Art
A lithography technique which leads development of micropatterning of a semiconductor device is a very important process which uniquely generates a pattern in semiconductor manufacturing processes. In recent years, with high integration of an LSI, a circuit line width required for semiconductor devices progressively decreases year after year. In order to form a desired circuit pattern on the semiconductor devices, a high-definition original pattern (also called a reticle or a mask) is necessary. In this case, an electron beam writing technique has an essentially excellent resolution and is used in production of a high-definition original pattern.
FIG. 15 is a conceptual diagram for explaining an operation of a conventional variable-shaped electron beam writing apparatus. A variable-shaped electron beam writing apparatus (EB (Electron Beam) writing apparatus) operates as follows. In a first aperture 410, a square, for example, rectangular opening 411 to shape an electron beam 330 is formed. In a second aperture 420, a variable-shaped opening 421 to shape the electron beam 330 having passed through the opening 411 in a desired square shape is formed. The electron beam 330 irradiated from a charged particle source 430 and having passed through the opening 411 is deflected by a deflector. The electron beam 330 passes through a part of the variable-shaped opening 421 and is irradiated on a target object 340 placed on a stage. The stage continuously moves in one predetermined direction (for example, defined as an X direction). More specifically, a square shape which can pass through both the opening 411 and the variable-shaped opening 421 is written in a writing region of the target object 340. A scheme which causes an electron beam to pass through both the opening 411 and the variable-shaped opening 421 to form an arbitrary shape is called a variable shaped beam scheme.
In this case, a position of the stage on which the target object 340 is placed is measured by a laser length measuring device. When the stage position is measured by the laser length measuring device, a mirror for reflecting the laser beam is arranged in the stage. The mirror reflects a laser beam emitted from the laser length measuring device. The laser length measuring device receives the laser beam reflected from the mirror to measure the stage position from an amount of displacement.
In moving the stage in an XY-direction, a pre-load fluctuation and the like are generated in the stage including an X-stage and a Y-stage due to machining accuracy of a guideway of each stage and a change in weight balance cased by the stage movement. For this reason, an error occurs in a distance between the mirror and a work fixing jig. Therefore, there is disclosed a technique of previously measuring a relative amount of displacement between the mirror and the work fixing jig, which is generated at each point where the stage is moved (see Japanese Patent Application, Publication No. S62-217686, for example). There is disclosed a technique of decreasing a pitching error when the stage is moved in a mechanism for moving the X-stage and the Y-stage by using a cross-roller guide (see Japanese Patent Application, Publication No. 2004-104001, for example).
In the techniques disclosed in the above publications, static deformation is corrected at each position when the stage is moved. However, in the writing apparatus, a displacement different from the static displacement is also brought about by an influence of acceleration or deceleration associated with the movement of the stage. That is, when the acceleration is applied, the displacement occurs in the position measured by the laser length measuring device. This results in a problem that a target object position to be recognized is shifted due to the displacement of the position measured by the laser length measuring device.